There is a general desire for wind turbine rotors to produce as much energy as possible for a given wind speed. However, the inner part of a wind rotor blade has to meet constraints related to structure, manufacturing and transport, which counteract measures for optimizing lift. The structural constraints include that the thickness of the wind turbine blade must increase towards a root section thereof.
The rpm of wind turbine rotors, their power output and load on the wind turbine blades is commonly conducted by controlling the pitch of the blades, i.e. the level of twisting of the blades into the wind. Generally, a decreasing pitch angle increases the load on the blades of the wind turbine rotor and hence the amount of energy that can be extracted from the wind at a given wind velocity. However, the pitch needs to be kept within limits in order to avoid aerodynamic stall or overload on the blades. In order to optimize power output, most modern wind turbines are equipped with pitch control systems for controlling the pitch angles of the blades based on measured or estimated parameters, such as output power.
One concern in the design of wind turbines is to safeguard components, which are subject to forces and torques, against overload occurring, for example, at extreme wind conditions, at the occurrence of gusts, or at sudden wind direction changes.